1. Field of the Invention
The invention relates to a liquid crystal display device, and more particularly to a light-reflection type liquid crystal display device.
2. Description of the Related Art
Since a portable terminal device such as a portable personal computer can accumulate power in limited amount, parts constituting a portable terminal device are required to consume small power. Accordingly, not a display unit which can emit light by itself, but a liquid crystal display device which consumes small power is predominantly used as a display unit for a portable terminal device.
However, a liquid crystal display device does not have a function of emitting light by itself, and hence, has to include a light source. In accordance with a light-source, a liquid crystal display device is grouped into a light-reflection type liquid crystal display device, a light-transmission type liquid crystal display device, and a combination type liquid crystal display device.
A light-transmission type liquid crystal display device has a back-light source by which the device can display images.
A light-reflection type liquid crystal display device includes a light-reflector therein, and uses external light entering into the device and reflecting at the light-reflector, as a light source. Hence, a light-reflection type liquid crystal display device is not necessary to include a back-light source unlike a light-transmission type liquid crystal display device.
A combination type liquid crystal display device includes a first section fabricated as a light-transmission type liquid crystal display device and a second section fabricated as a light-reflection type liquid crystal display device.
A light-reflection type liquid crystal display device consumes smaller power and can be fabricated thinner and lighter than a light-transmission type liquid crystal display device, and hence, is mainly used as a display unit for a portable terminal device. This is because a light-reflection type liquid crystal display device uses external light entering thereinto and reflecting at a light-reflector for displaying images, and hence, is necessary to have a back-light source unlike a light-transmission type liquid crystal display device.
However, since a light-reflection type liquid crystal display device uses external light as a light source, it is difficult or almost impossible for a user to clearly see displayed images, if it is dark around the device.
In order to solve such a problem, a light-reflection type liquid crystal display device designed to include a preliminary light source which supplies light to the device through a light-guide has been suggested, for instance, in Japanese Patent No. 2699853 (Japanese Patent Application Publication No. 7-199184), and Japanese Patent Application Publications Nos. 11-149252, 11-219610 and 2000-147499.
FIG. 1 is a cross-sectional view of an example of a conventional light-reflection type liquid crystal display device including a preliminary light source.
A conventional light-reflection type liquid crystal display device 100 illustrated in FIG. 1 is comprised of a liquid crystal display panel 101, a polarizer 102 lying on the liquid crystal display panel 101 in such a direction as facing a viewer, a light-guide 103 mounted on the polarizer 102, a light source 104 located adjacent to an end of the light-guide 103, and supplying light to the liquid crystal display panel 101 through the light-guide 103, an operation panel 105 arranged above the light-guide 103 for operating the liquid crystal display device 100, and a chassis 106 supporting the liquid crystal display panel 101.
Light emitted from the light source 104 reaches the polarizer 102 through the light-guide 103, is polarized when passing through the polarizer 102, and reaches the liquid crystal display panel 101 to thereby be used for displaying images.
Hereinbelow is discussed as to how the operation panel 105 is supported. FIG. 2 is a cross-sectional view of another conventional light-reflection type liquid crystal display device 110. Parts or elements that correspond to those of the liquid crystal display device illustrated in FIG. 1 have been provided with the same reference numerals.
In the liquid crystal display device 110 illustrated in FIG. 2, the light source 104 is covered with a frame 107 which is open only to the light-guide 103. A shield 108 having a reverse-L shaped cross-section is coupled to the chassis 106. The operation panel 105 is supported at its opposite ends on the shield 108, and fixed to the shield 108 through double-sided adhesive tape (not illustrated).
FIG. 3 is a cross-sectional view of still another conventional light-reflection type liquid crystal display device 120. Parts or elements that correspond to those of the liquid crystal display device illustrated in FIGS. 1 and 2 have been provided with the same reference numerals.
In the light-reflection type liquid crystal display device 120, the operation panel 105 is supported at a left end on the frame 107, and at a right end on the chassis 106.
As mentioned earlier, a liquid crystal display device is incorporated in various portable terminal devices because of small power consumption. A portable terminal device is presently required to fabricate smaller, and accordingly, a liquid crystal display device used in a portable terminal device is required to fabricate smaller, specifically, thinner, shorter and/or lower.
Considering the conventional light-reflection type liquid crystal display device 110 illustrated in FIG. 2 in view of such requirements, since the shield 108 is sandwiched between the operation panel 105 and the frame 107, the light-reflection type liquid crystal display device 110 has to be thicker to a degree corresponding to a thickness of the shield 108.
The conventional light-reflection type liquid crystal display device 120 illustrated in FIG. 3 has to be longer in width to a degree corresponding to a width A of the chassis 106 on which the operation panel 105 is supported at a right end.
As mentioned above, a structure for supporting the operation panel 105 makes it difficult for a liquid crystal display device to be fabricated thinner and shorter in the conventional light-reflection type liquid crystal display devices.
In addition, though the shield 108 is frame-shaped in the conventional light-reflection type liquid crystal display devices 110 and 120 illustrated in FIGS. 2 and 3, the shield 108 cannot provide performance associated with its size.